[GreenKeys] M28 reperfs

[Duncan Brown]

Is there a document that lists all the different M28 reperf "LPR" models 
and  what is different about each?

I'm working on a TT-253A (thanks to Nick!) that does not have a standard 
reperf in it.  The TT-253A is supposed to use a LPR53AWA (full perf, 
tape feed out, backspace).  What is in this unit is a LPR13XXX 
(chadless, tape feed out, no backspace). The unit punches fine (after I 
re-hooked up a spring in the Selector Magnet area), but can't check the 
printing yet due to missing print hammer (one on order from Nick).

In checking out the "Tape feed-out" function - the tape feed-out 
solenoid operates (and buzzes) and the ratchets turn but no tape out. I 
think this is the version that tape-out is suppressed by incoming 
message (there is an arm going up towards the SM armature), but can't 
see why it is not releasing the function clutch when running closed.

Also confusion between different manuals about whether the tape feed-out 
solenoid is supposed to operate on 115V AC or 115V DC. 1963 vintage 
manuals (eg NAVSHIPS 94456) show TT-253A using LPR53AWA reperf with 
solenoid L5850 (TC # 274); 450 ohms; 115VDC. Wiring diagrams show the 
LTRK5 base with a series resistor & diode and parallel capacitor to 
supply the 115VDC. But this LTRK5 base has the resistor & diode replaced 
by wires and the capacitor removed.

I thought that the removal of the 115VDC parts could have been a later 
modification. (Besides the change of LPR unit, this TT-253A had the 
power & signal lines soldered directly to the blue Amphenol 16 contact 
ribbon connector!) (I've ordered the mating connector)

Then I got a hold of the NAVELEX 0967-LP-616-7010 (APR 79) manuals and 
they show the LTRK5 base and LPR53 wired for 115VAC!!

I'm getting confused!

The reperf in this TT-253A is a LPR13XXX, with a tape-out solenoid #252 
and measures 200 ohms and it does not look like any of the drawings in 
any of the manuals. (Pictures enclosed)  I've read how the tape-out 
mechanism is supposed to work, but had trouble following it, especially 
in that my unit seems different from what the manuals are talking about.

When I energize the solenoid, the timing ratchets rotate, but nothing 
else happens.  I've tried pushing & pulling (gently) the various levers 
in the area, but nothing trips the function clutch. I'll put in the 
parts to put DC on the #252 solenoid, but I don't think it will affect 
the tape-out.

This dissertation was partly just to get my thoughts & facts together, 
but if anyone has any ideas about the tape-out mechanism, I'd like to 
hear them.

Thanks,

Duncan
K2OEQ





-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20250602/bf7aa480/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: LPR13XXX tape-out side.jpg
Type: image/jpeg
Size: 4866152 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20250602/bf7aa480/attachment-0002.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: LPR13XXX tape-out top.jpg
Type: image/jpeg
Size: 3902837 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20250602/bf7aa480/attachment-0003.jpg>